Archimerged invents the TrombePump Heat Engine

Well, it's not really the first TrombePump, but it is the first TrombePump heat engine. See Brian White's Pulser Pump at his tripod website (you need this popup blocker), and Dr. Masao Kondo's Geyser Pump. Archimerged did at least coin the term. Brian White's pump is a water pump that runs essentially forever (20 years and counting) with no energy input except water flow down a stream. Brian does have a page labeled "heat engine" but it is not the conventional use of the term: he describes an engine that produces heat, not an engine that runs on heat. (Not that getting free heat from otherwise useless low head hydro power is a bad idea, but it's not a heat engine).

Anyway, the TrombePump is a no-moving-parts contraption which produces compressed air from the flow of solar energy out into space, by way of a solar water heater, atmospheric ambient heat, and nighttime "cold". It is a combination of a trompe or trombe air compressor, together with an air-lift or bubble pump. Archimerged imagines that one ought to fit into the space occupied by the gasoline tanks underneath filling stations, so that cars could be powered by compressed air produced in-situ at filling stations. And even if bigger water tanks are needed, there is plenty of space underground where they can be built, and water is cheap when used in a closed cycle.

A quick calculation regarding how much water is needed for an AirCar filling station:

  • watts (of gasoline flow) moving through a gasoline station averages about 3 MW:
  • joules per liter of water ≈ 124 kJ/liter
    • Delta T = 30K
    • Heat capacity of water = 4.183 J/g/Kelvin
    • Density of water is more than 992 kg/m^3 (depending on temperature).
    • (30 K) (4.183 J/g K) (1000 kg/m^3) = 125.49 kJ/liter
    • (30 K) (4.183 J/g K) (992 kg/m^3) = 124.48608 kJ/liter
  • Water needed per joule invested in compressing air = (1/124) liter/kJ = 8 liter/MJ
  • joules of heat stored to produce 3 MW work:
    • Expected temperature variation: 273K to 303K (perhaps a little optimistic)
    • Work available over that variation: 10% of heat flow.
    • Time over which temperature variation occurs = 24 hours
    • (3 MW) (10 watt / 1 watt) (24 hours) = 2592 GJ
  • Volume water to produce 3MW work storing heat and "cold" over 24 hours:
    • (8 liters/MJ) (2592 GJ) = 20736 m^3
  • Side of cube of that volume:
    • (20736)^(1/3) m = 27.473142 meters
  • Diameter of sphere of that volume (4/3 π r^3) and units defines slash so a / b c = a / (b c):
    • 2 (20736 / (4/3) pi)^(1/3) m = 34.085954 m

So we need a pretty big water tank, two of them that size actually. But you don't have to keep filling them up, unlike the gasoline tanks.

I am presently producing a nice diagram using inkscape, and I'm also writing exactly what I did in inkscape to make the diagram. Then I hope to release the tutorial about how to make this diagram in inkscape, and get more readers.

The TrombePump Heat Engine is what I was describing a few days ago.

Obviously, the AirCar filling stations will also have an electric motor / generator attached to an efficient rotary air compressor / motor. (Maybe Archimerged's eponymous Submerged Archimedes Screw air compressor would serve. Probably not, because electricity generation needs high rotational velocity). On days when not enough heat or "cold" is collected, the station buys electricity from the grid. On other days when excess compressed air is produced, the station sells electricity to the grid.

Also, the AirCar needs high pressure compressed air, P ≈ 4500 psi ≈ 300 atm ≈ 31 MPa ≈ 3.2 km H2O head. The TrombePump produces air at a pressure equal to the hydraulic head. If a 200 meter tower is used, the head must be wrapped around 16 times to get 3.2 km H2O head. You need 16 separate TrombePumps with the high-pressure side of one connected to the low-pressure side of the next.


3 Responses to “Archimerged invents the TrombePump Heat Engine”

  1. 0xff Says:

    We say Al Gore’s “An Inconvenient Truth”, very good, I recommend it. He points out that one problem with Archimerged’s suggestion for Air Stations, is that the energy compainies won’t have anything to truck around (maybe this is a Teamster concern more than an energy company concern.) Yet it does run smack up against another great point in the movie:

    “it is difficult to get a man to understand something when his salary depends upon his not understanding it.”

    — upton sinclair

    So to get this off the ground, it will be necessary for salary issues to be done away with — sounds to me like a calamity is just the thing, a real falling apart of the old (current) world order to make people change directions.

  2. William Says:

    The diagram of the TrombePump Heat Engine is signally lacking in indications of relative elevation of the four principal components.

    Also there is NO indication of heat flow into and out of the apparatus.

    “…the TrombePump is a no-moving-parts contraption which produces compressed air from the flow of solar energy out into space, by way of a solar water heater, atmospheric ambient heat, and nighttime “cold.” Now is the time to be explicit and show where the atmosphere ambier heat, enters the engine (system); where the “flow of solar energy out into space,” occurs; identify the solar water heater; and where/how nightime “cold” is involved.

    Re:Oxff’s comments. A viable working system must first be demonstrated, whether it is the TrombePump Heat Engine, or the Air Car.
    FYI compressed air is a very useful means of supplying energy to/for a variety of purpose, unfortunately an automobile is not one of them.
    IIRC Eastman Kodak had an air locomotive to shut rail cars around it plant and minimize soot and cinder contamination of the photographic film manufacturing operations in Rochester, N.Y. It was refilled/recharged from a stationary air compressor at their steam plant.

  3. archimerged Says:

    Sorry about drawing deficiencies. A later version will correct that. The trompe side with siphon inverted U is higher than the other side. It can be up to 30 feet higher because atmospheric pressure forces the water up and over the inverted U. I expect it would be only a foot or two higher. The bubble nozzle must be at a point where the hydrostatic pressure is less than atmospheric.

    Heat flows in from the "hot heat source" and out into the "cold heat sink" which are labeled in the drawing. However, heat could also flow into the bubble pump tower and out of the trompe tube, depending on the engineering decisions. A large amount of heat is stored in the countercurrent heat exchanger between the two tubes.

    Ambient heat and solar heat enter from large solar collector panels of any usual design, probably including solar concentrator. Ambient heat is collected as in an air-source heat pump, using fins on copper pipes carrying refrigerant. This could be a powered heat pump or just a heat pipe. I'm not presently in the business of designing ambient heat collectors, but soon I need to calculate how much heat flow I can get. I do know that if I allow a larger temperature drop, more heat will flow.

    Ambient "cold" is used like a room air-conditioner, fins on a copper tube containing refrigerant, this time, the heat pipe carrying heat out of the cold temperature reservoir. Solar energy flows out into space naturally all the time, probably at the same rate all the time. Any hot object radiates infared some of which goes all the way out into space. That phrase was not meant to be something special or unusual, but just describing the fact that this engine simply captures a very small fraction of the solar energy that flows by whether we use it or not. At the moment, such energy mostly is "used" to evaporate water causing weather.

    Nighttime cold and daytime heat are used because of the large thermal mass in the countercurrent heat exchanger (see  TrombePump countercurrent heat exchanger design).  Gravity feed heat pipes, which carry heat only upward, serve to collect heat during the day.  The bottom of those heat pipes have fins exposed to ambient air, and the tops lead up into a temperature reservoir just slightly cooler than ambient.  A different set of heat pipes leading up from a cold temperature reservoir collect "cold" at night.   The art of collecting ambient temperature heat is not well developed.  I plan to do more calculations regarding this, and expect to show that there is a lot of energy available there.
    The AirCar does work and is in production. Google for AirCar. It has a special engine which lets the compressed air expand in four steps, running through four cylinders one at a time, and being re-heated between steps.

    I would be interested in adding external combustion to the AirCar, as I suspect you could get much higher mileage from a given amount of compressed air if you heat it first using say a catalytic converter burning some renewable fuel.

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